P0175 on the 2024 GMC Sierra: V8 Truck Diagnosis
The 2024 GMC Sierra 1500 is available with several engine options, most commonly the 5.3L V8 (L84, 355 hp) or the 6.2L V8 (L87, 420 hp). Both are GM's Gen V small-block engines with Active Fuel Management (AFM) or Dynamic Fuel Management (DFM) cylinder deactivation, direct fuel injection, and variable valve timing. These V8 engines have a true Bank 2 — the passenger side containing cylinders 2, 4, 6, and 8.
P0175 on the Sierra means the ECM has detected that Bank 2 is consistently running too rich, with fuel trims exceeding the system's correction capability.
Symptoms
- Check engine light on
- Fuel economy below the expected 16-23 MPG range
- Rough idle, possibly with AFM/DFM-related hesitation
- Rich exhaust smell
- Black soot on tailpipe
- Reduced power under load or towing
- Cylinder deactivation may behave erratically
Top Causes for the Sierra's V8 Engines
1. MAF Sensor Contamination — High Likelihood
The Sierra's MAF sensor sits in the large-diameter intake duct and is exposed to truck-typical dust and debris. GM's DI engines also run significant PCV flow that introduces oil vapor to the intake tract. On the 5.3L and 6.2L, even small MAF reading errors affect fuel delivery across four Bank 2 cylinders simultaneously. Cleaning with MAF-specific spray is worth trying, but replacement with a quality AC Delco unit ensures accuracy.
2. O2 Sensor Degradation — Medium Likelihood
The upstream wideband O2 sensor on Bank 2 is the primary feedback mechanism for closed-loop fuel control. GM's V8 exhaust manifolds run hot, and the sensor is positioned close to this heat source. Even on a newer 2024 model, a sensor with a factory defect can cause P0175. Testing with a GM-specific scanner (Tech 2 or GDS2) reveals response time degradation.
3. Fuel Injector Issues — Medium Likelihood
The Gen V 5.3L and 6.2L use direct fuel injection with high-pressure injectors. These injectors are precision components that operate at pressures exceeding 2,000 PSI. Carbon buildup on injector tips, a common issue with GDI engines, can alter spray patterns and cause uneven fuel delivery. A Bank 2 injector that over-delivers pushes that bank's fuel trims negative.
4. EVAP Purge Valve — Low Likelihood
GM trucks have a known history of EVAP purge valve issues across multiple model years. A purge valve stuck in the open position feeds fuel vapors into the intake continuously, enriching the mixture. On the Sierra, this valve is usually accessible on the engine's intake side and is an affordable replacement part.
Diagnostic Steps
- Scan for all codes with a GM-compatible scanner
- Monitor fuel trims at idle and 2,000 RPM — compare Bank 1 vs Bank 2
- Test MAF sensor output against GM specifications
- Monitor O2 sensor response and voltage patterns
- Check for EVAP purge valve issues
- Test fuel pressure at the high-pressure rail
Repair Costs
- MAF sensor: $100–$260
- O2 sensor: $120–$300
- Fuel injector (each): $150–$350
- EVAP purge valve: $60–$150
The 2024 Sierra is covered by GM's 3-year/36,000-mile bumper-to-bumper warranty.
DIY or Dealer?
The Sierra's engine bay offers good access for basic repairs. MAF sensor and EVAP purge valve are straightforward DIY jobs. O2 sensor access on Bank 2 requires working under the truck. GDI fuel injector work on the high-pressure system should be handled by professionals. For warranty-covered vehicles, the dealer is the best first stop.